krejci



Sept. 10, 1963 J. c. KREJCI PRODUCTION OF CARBON BLACK Filed April 14,1960 INVENTOR. J C KREJCI H JAM A TTORNEVS United States Patent3,103,418 PRODUCTION OF CARBON BLACK Joseph C. Krejci, Phillips, Tex.,assiguor to Phillips Petroleum Company, a corporation of Delaware FiledApr. 14, 1960, Ser. No. 22,350

6 Claims. (Cl. Z3209.4)

This invention relates to the-production of carbon black. In onespecific aspect it relates to the production of carbon black in afurnace by pyrochemical action in which the properties of the carbonblack are improved by the presence of chlorine compounds in thehydrocarbon feed. 'In another aspect it relates to the production ofincreased yields of carbon black by comparison to yields normallyproduced in such a furnace.

It is known in the prior art to produce carbon black by directing a hotoxidizing or combustiongas in a generally helical path adjacent theperiphery-of a generally cylindricalreaction zone and directing areactant material axially into said zone inside the helically-moyingmass of hot gas. The reactant is thereby rapidly heated to a carbonblack-forming temperature, e.g., in the range 2200 to 3500 F., andreacted in said zone to form carbon black, which is subsequentlyrecovered. Another tangential flame type process involves the injectionof a combustible mixture of fuel and oxidizing gas circumferentiallyinto a combustion zone and the reaction of the mixture by combustionnear the periphery of said zone. The resulting combustion gas, at ahightempera- :ture, travels in a generally spiral path toward the axisof a combustion zone and is then directed in a generally helical pathadjacent the periphery of the reaction zone Whichis contiguous with, ofsmaller diameter than, and in open communication with, said combustionzone. A carbonaceous reactant is directed alongthe common axis of saidzones and is rapidly heated to a carbon blackforming temperature byvirtue of heat directly imparted from the helically-moving combustiongas. The reactant is converted within the reaction zone to form carbonblack, which is subsequently recovered. This type of tangential-flameprocess is known as a precombustion process, since the hot gas issubstantially completely formed by combustion prior to contact with themac taut.

The reaction mixture formed in the process of the type above describedcomprises a suspension of thecarbon black in combustion gas. art towithdraw such a mixture from the reaction zone and'to cool the mixturesuddenly by the direct injection thereinto of a cooling liquid, such aswater, in order to cool the mixture suddenly to a temperature at whichno :further reactionv can occur. The carbon black is then separatedtherefrom by any usual means old in the art, such as running theefliuent through bags to screen out the carbon black.

I have found that by the prior mixing on? a chlorine compound with thehydrocarbon axial feed to said combustion and reaction zones, increasedyields of carbon black are obrtained. .Th e chlorine compound employedcan be anychlorine compound that will liberate chlorine, preferablychlorinated hydrocarbons. I have further foundthat when the carbon blackso produced is compounded "according to conventional rubber tread stockrecipes, a rubber is produced having superior qualities in modulus,resilience, and abrasion resistance.

One object of thisjinvention is to provide an improved process forproducing carbon black.

Another object of this invention is to provide a process for producingan improved carbon black capable of imparting high abrasion resistanceto rubber compounds in which said carbon black is'added.

It is known in the prior "ice FIGURE 2 is a longitudinal sectionalviewthe same furnace taken online 2-2 of FIGURE 1...

The process of this invention is directed to producing a substantiallytar-free carbon blackv having a photelometer value of at least 86. Thetar contentofi carbon black is determined by mixing 2 grams ofblackwiflh- 50 cc. of chloroform, boiling the mixture, filtering, anddetermining the percentage light transmittance of a blank sample ofchloroform. The. comparison is preferably conducted with a photoelectriccolorimeter suchas a Lumetron colorimeter'at a Wavelength-of 440 mu, alight intensity of 20", and cell one centimeter long. A tar-free blackis arbitrarily defined as one that shows in tests on samples taken afterpelletinga transmittance greater than 85 percent according to thisprocedure. Pelleting the flocculant black by a conventional processraises the photelometer number five points, or more, from to 85, forexample. 7 l

Chlorinated hydrocarbon compounds, such as carbon tetrachloride,chloroform, and ethylene dichloride can be employed in practicing theprocess of this invention. The chlorine compound is added to thehydrocarbon feed so as to have a concentration of said chlorinein saidfeed in the range of 1 to 1 0 percent by weight, preferably 2 to- 5percent.

Referring now to the drawing which illustrates one form of apparatus inwhich the process of my invention maybe practiced, a cylindricalreaction chamber 10 has a lining 11 of highly refractory material.Between this refractory liner 11 and a cylindrical steel shell 13 is alayer of insulation 12. At the upstream end of' chamber is a shortcylindrical section 14 of rather large diameter called a combustionzone. This section has a refractory lining 11 and an insulation layer12".

In the upstream or inlet Wall of the combustion zone 14 of the turnaceis a feedpipe l6 arranged axially so that feed introduced therethroughwill pass axially through the furnace. Surrounding this feed pipe 16 isa larger pipe 17, defining an annular space litthrough which it isintended to pass air into the furnace. 'Air passing through this,annular space 18 is intended to keep the inner end of the feed tubecooled to prevent the deposition of carbonthere'on.

In the combustion zone 14 inlets i1-5 are so disposed that gas and airpassingtherethrough and intothe combustion zone will do soinadi'rection' tangent to the cylindrical ivall's. Each inlet contains asmall gas conduit :19 completely surrounded'by a' larger air conduit 20,with said gas conduit passing through a'conduit 21 and terminating in alarger conduit 22 which later terminates as an opening in the refractoryliner 11 of the combustion chamber wall. Air conduit ztlnjterminateswithin said conduit 21. Through this burner assembly is passed-acombustible mixture of fuel gas, such as natural gas, in anoxygen-containing gas, such as air. This combustible mixture is intendedto being burning as soon as it leaves conduit 19. Burning gas and flame,and air, and

the hot products of combustion then flow circumferentially around thewall of the the combustion zone (14.-

Upon continued injection of the combustible fuel mixture, the flameandcombustion products follow 'aspiral path until the diameter of thespiral becomes less than the a diameter of the reaction zone 10. By thistime it is intended that substantially all of he gaseous fuel has beenconsumed, and the hot combustion products then follow a helical pathadjacent a cylindrical wall to the reaction zone.

'I 'will hereinafter describe the production of a superior carbon blackusing an oil feed having the following characteristics:

A.S.T.M. D'ISTILLATION In the inventive process for the production ofcarbon black With a heavy hydrocarbon oil, describe above, as a sourceof carbon, the oil is mixed with a chlorine compound such as carbontetrachloride so that the concentration of chlorine is in the range ofV1 to 10 percent by Weight, preferably 2 to 5 percent. The feed mixtureis preheated to about 765 F. and introduced at this temperature throughthe tube 116 of FIGURE 2 into the cornbustion end of the i urnace. Thistube 16 is a inch I.D. tube centered in a inch iLD. air jacket tube 17.Air is added to the furnace through the annulus 1 8 at the rate of about1400 c.f.h. Air so added may be varied as desired, the important pointbeing to maintain the dis charge ends of the tubes .16 and .17sufficiently cool to prevent deposition of carbon thereon in case somecarbon is formed. The air is intended to remove the carbon blackcombustion.

In the examples given hereinafter, the tangential fuel inlet assembly ofFIGURE .1 was used. The openings 22 'were 4% inches in diameter and thetubes :19 extended into the opening 212 as shown. 'Ilubes 19 were ofinch ID.

The following is an analysis of the tangentially injected fuel gas:

Gas volume, percent This fuel gas and air were mixed in the proportionsof 23,040 c.f.h. of air to 1,560 c.f.h. of gas and the resultingcombustible mixture injected through the tangential inlets 1'5 at'avelocity greater than the rate of flame propagation. By this rapid rateof fuel mixture injection the danger of an explosion in the fuel lineswas averted.

To illustrate the eifectiveness of the inventive process the followingruns were made and the results noted in Table I. Conditions of operationnot noted in the table were as indicated previously.

.The combustion chamber 14 was 15 inches in diameter by 4% inches long;the reaction zone was 4 inches, in diameter by 5 feet long.

. a Table l Carbon Phoon Black tel- Surface Run No. Chlorine MaterialAdded Rate, Yield, ometer Area gaL/hr. lbs/gal. Value 1 None 27.9 .98 88144.9 2 5 Wt. percent 0014 29.8 3 32 90 143.0 3 5 Wt. percent O2H4Cl327.9 20 92 148.4

Samples of 'carbonblaok from the above mentioned runs 1, 2, and 3 weremade up in rubber compounds and vulcanized to finished rubber. Thecompounding formula used for this evaluation, was a conventional butyltread recipe and was as follows:

Parts by Weight Butyl 2117 1 100 Carbon black 50 Zinc oxide 5 Stearicacid 1 Form 40 2 1O Methyl Tuads 3 1.1 Altax 4 1.1 Sulfur 2 Elastopar 50.6

1 Isobutylene/isoprene copolymer containing 97.5% isobutylene 61-7O ML8at 212 F.

2 Plasticizer oil comprised of 66% paraffins, 6% first acidifins, 25%second acidifins, 3% nitrogen bases.

3 Tetralnethylthiuram disulfide.

4 Benzothiazyl disnlfide.

G N-methyl-N,d-dinitrosomethylaniline.

givenin Table II. However, the values reported in columns headed ModulusIndex, Resilience Index, and Abrasion Index were obtained from samplescompounded as above mentioned, vulcanized for 30 minutes, and thevulcanized samples aged for 24 hours at 212 .F., prior to thedetermination of the modulus index, abrasion index, and resilienceindex.

Table II I Test Samples Vulcanized 30 Test Samples Vulcanized 30 MinutesMinutes, Then Aged 24 Hrs.

2l2 F. Run No.

300% Tensile Elonga- Modulus Resil Abrasion Modulus, Strength, tion,Index ience Index p.s.i. p.s.i. Percent Index In Table II, the term 300%Modulus p.-s.i. refers to the pounds per square inch pull in the tensiontests when the test piece of vulcanized rubber has been stretched 300percent of the length of the original test piece. The Tensile Strengthp.s.i. column represents the pounds per square inch pull at the point ofrupture or break of the test piece undergoing the above mentioned 300percent modulus test. The Elongation column represents the stretch ofelongation at the point of break. Resilience is a measure of potentialenergy of a piece of rubber that is present as a result of the'applied,stress and which is recoverable when the stress is (removed. Abrasion isa loss in weight of a test piece of rubber of standard size when'exposedto standard abrasion conditions. The rubber compounded and vulcanizedcontaining the chlorine free carbon black of run- -1 was assigned theindex number of 100. Index values of runs 1, 2, and 3 thereby provide abasis for comparing and evaluating performance of the various carbonblacks.

In each case where the chlorine compound was added tothe oil feed to thecarbon black furnace, a rubber significantly superior in abrasion,resilience, and modulus was obtained. Upon comparing runs 1 and 2 ofFable I it is noted that the oil rate was seven percent higher and theyield was increased by -11 percent, yet surface area values for the twoblacks were essentially the same. The advantages of thus producing acarbon black wherein the oil feed to the carbon black furnace containschlorine are at once obvious.

An additional run was made to compare the carbon black produced by theinventive process to the carbon black produced by the process describedin US. 2, 5 87,107. That patent described the production of a carbonblack having more tar than usual. The tar was removed from the recoveredblack by liquid extraction using a chlorinated hydrocarbon solvent. Tarsrecovered along with a small portion of the chlorinated solvent werethen added to the oil feed for recycling.

Run 4 was made under the same operating condition as run 3 except thatthe oil rate was set percent higher, producing a carbon black having aphote-lometer value of 14. This carbon black was extracted as notedabove, producing a carbon black having a nitrogen surface area of 107.8sq. m./-g. This carbon black 'was then compounded in a rubber-recipe aswere runs 1, 2, and 3, vulcanized, and aged under the same conditions.Results are noted in Table III where data obtained in runs 1 and 2 arerepeated for convenience of comparison.

It is obvious that the extracted black is not equivalent to the carbonblack produced by the inventive process with respect to rubberreinforcement performance, as significantly lower modulus and abrasionindices were obtained.

As will be evident to those skilled in the art, various modifications ofthis invention can be made, or followed, in the light of the foregoingdisclosure and discussion, without departing from the spirit or scopethereof.

I claim:

1. In a continuous furnace carbon black producing proc-v ess comprisingthe continuous steps of passing a hydrocarbon feed into a carbon blackfurnace, heating. said hydrocarbon in said furnace to convert a portionof said hydrocarbon to a carbon black by a pyrochemical crackingoperation in a first zone in said furnace, cooling the efliuentresulting carbon black containing gases, and separating said carbonblack and said gases; an improvement which comprise-s adding achlorine-liberating compound to said hydrocarbon feed in an amountsuflicient to increase the yield of said carbon black and to producesaid carbon black in a substantially tar-free state.

2. The process of claim 1 wherein the concentration of chlorine in saidhydrocarbon feed is in the range of 1 to 10 percent by weight.

3. The process of claim 1 wherein the concentration of chlorine in saidhydrocarbon feed is in the range of 2 to 5 percent by weight. I

4. The process of claim 2 wherein the chlorine compound added to thehydrocarbon feed is a chlorinated hydrocarbon.

5. The process of claim 4 wherein said chlorinated hydrocarbon is carbontetrachloride.

6. The process of claim 4 wherein said chlorinated hydrocarbon isethylene dichloride.

References Cited in the file of this patent UNITED STATES PATENTS1,259,121 Mott Mar. 12, 1.918 1,891,859 Winter Dec. 20, 1932 2,58 7 ,107Cade Feb. 26, 1952 2,632,713 Krejci Mar. 24, 1953 2,665,194 Jordan Jan.5, 1954

1. IN A CONTINUOUS FURNACE CARBON BLACK PRODUCING PROCESS COMPRISING THECONTINUOUS STEPS OF PASSING A HYDROCARBON FEED INTO A CARBON BLACKFURNACE, HEATING SAID HYDROCARBON IN SAID FURNACE TO CONVERT A PORTIONOF SAID HYDROCARBON TO A CARBON BLACK BY A PYROCHEMICAL CRACKINGOPERATION IN A FIRST ZONE IN SAID FURNACE, COOLING THE EFFLUENTRESULTING CARBON BLACK CONTAINING GASES, AND SEPARATING SAID CARBONBLACK AND SAID GASES; AN IMPROVEMENT WHICH COMPRISES ADDING ACHLORINE-LIBERATING COMPOUND TO SAID HYDROCARBON FEED IN AN AMOUNTSUFFICIENT TO INCREASE THE YIELD OF SAID CARBON BLACK AND TO PRODUCESAID CARBON BLACK IN A SUBSTANTIALLY TAR-FREE STATE.